Muscle of expiration:

Ans. B Internal intercostalsa. Expiration:i. During expiration, the diaphragm simply relaxes, and the elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs.ii. During heavy breathing Expiration extra force is achieved mainly by contraction of the abdominal musclesiii. Muscles that pull the rib cage down ward are classified as muscle of expiration: - are Abdominal recti powerful effectInternal intercostals muscles.b. Inspiration: -a. Contraction of Diaphragm is a most important in inspiration.b. Muscle that elevate the chest cage are classified as Muscles of inspiration: - arei. External intercostals most important muscles that raise the rib cageii. Sternocleidomastoid, Anterior serrati, and scaleni ~ that help in the raising the ribs cage.